| In this work, I report on the case study of LVW, a 40 year old female, who has developmental prosopagnosia. Prosopagnosia is a face processing disorder characterized by the inability to recognize faces in the absence of severe intellectual, perceptual, or memory impairments. Even though prosopagnosia generally manifests itself after some type of injury to the temporal or occipital areas of the brain, a very small number of cases of developmental prosopagnosia have been reported. LVW presents such a case.; Structural magnetic resonance imaging (MRI) revealed no overt brain abnormalities. Basic visual skills, including contrast sensitivity, were normal. LVW could make face/non-face judgments. She classified sex and facial expressions with the same accuracy as controls. LVW consistently rated faces as being more typical than normal controls did. LVW was poor at visual identification of famous faces and discrimination of famous and non-famous faces, but not names. Unfamiliar face recognition was also poor and dropped to chance level or below when faces were tested in a view different from the learned view. LVW's response times to faces were significantly slower than normal controls'. LVW shows normal recognition of everyday objects. Further, recognition of highly similar objects belonging to the same category was within the normal range of the control group's performance, although her response times were generally slower. LVW did not show an inversion effect for faces, and she showed a significantly higher false alarm rate to conjunction faces. These results suggest a feature-based approach to face processing. Placing LVW's face recognition deficits in the framework of the Bruce and Young model of face recognition, she appears unable to extract invariant information or establish reliable structural codes for faces. Instead she relies on the pictorial code inherent in the stimuli to aid recognition. The structural codes used to establish individual face recognition units appear tenuous. Thus, the face recognition units appear not to be very well established. Further, once established, the face recognition units are prone to suffer from interference from faces of persons that appear similar or share common characteristics. |
